首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   64644篇
  免费   6323篇
  国内免费   1463篇
耳鼻咽喉   533篇
儿科学   1510篇
妇产科学   1029篇
基础医学   5585篇
口腔科学   1969篇
临床医学   5669篇
内科学   10239篇
皮肤病学   803篇
神经病学   4557篇
特种医学   1585篇
外国民族医学   4篇
外科学   6176篇
综合类   7270篇
现状与发展   5篇
一般理论   3篇
预防医学   9390篇
眼科学   776篇
药学   5425篇
  30篇
中国医学   5088篇
肿瘤学   4784篇
  2024年   204篇
  2023年   1437篇
  2022年   2840篇
  2021年   3382篇
  2020年   2870篇
  2019年   3156篇
  2018年   3221篇
  2017年   2589篇
  2016年   2181篇
  2015年   2167篇
  2014年   4509篇
  2013年   4449篇
  2012年   3612篇
  2011年   3882篇
  2010年   3024篇
  2009年   2810篇
  2008年   3082篇
  2007年   3181篇
  2006年   2731篇
  2005年   2291篇
  2004年   1923篇
  2003年   1840篇
  2002年   1365篇
  2001年   1212篇
  2000年   998篇
  1999年   898篇
  1998年   808篇
  1997年   776篇
  1996年   579篇
  1995年   554篇
  1994年   482篇
  1993年   385篇
  1992年   385篇
  1991年   332篇
  1990年   275篇
  1989年   262篇
  1988年   257篇
  1987年   194篇
  1986年   167篇
  1985年   189篇
  1984年   167篇
  1983年   114篇
  1982年   121篇
  1981年   109篇
  1980年   112篇
  1979年   84篇
  1978年   59篇
  1977年   53篇
  1976年   30篇
  1975年   29篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
学生课堂教学质量评价问题浅析   总被引:1,自引:0,他引:1  
综合分析河南中医学院近三年以来学生课堂教学质量评价反馈的信息,认为引发课堂教学评价偏差的人为因素有评价者的能力水平、责任心、情感倾向。其对策为:改变教师的被动地位,进一步修订评价体系,加强对组织评价者的培训,强化临床课的教学,进一步提高学生的认识,跟踪调查课堂教学质量评价。  相似文献   
32.
目的:观察核心结合因子a1(Cbfa1)对兔骨髓间充质干细胞(MSCs)向成骨细胞分化的诱导作用。方法:体外分离培养兔骨髓MSCs,用AdEasy1/Cbfa1。转染MSCs,在转染后3d,1、2、3和4周时,组织化学和免疫组化等方法检测成骨标志碱性磷酸酶和骨钙素的表达。结果:AdEasy1/Cbfa1转染后的兔骨髓MSCs表现出与成骨细胞相似的形态,并且表达碱性磷酸酶和骨钙素。结论:Cbfa1可诱导兔骨髓MSCs向成骨细胞分化。  相似文献   
33.
上海市某区警察心理健康状况和生活质量的时点调查   总被引:12,自引:3,他引:9  
目的调查警察心理健康状况和生命质量的基本流行学资料。方法采用梅奥心理服务问卷,主要内容为心理健康状况和生命质量测定等。在上海市某公安分局内进行截断面时点调查。结果1共调查警员1611人,男性91.5%,女性8.5%,年龄28.8±17.5岁。2GHQ的平均得分:1.5±2.31,存在可能心理障碍倾向者比例15.3%,可能存在重度心理障碍者比例2.9%。3SCL-90总分大于160分者比例17.2%;单项分大于2分比例最高的是强迫症状因子(19.5%),睡眠饮食因子次之(12.8%),躯体化症状因子(12.6%)第3位,敌对因子(12.4%)处于第4位。4健康变化、总体健康感、心理健康和生命活力得分是相对最低的维度。结论1在警察群体中存在心理障碍者比例远高于一般市民,生活质量一些维度相对较差;2建立长效机制是维护和保证警察心理健康和生活质量的有效手段。  相似文献   
34.
Three recent sequential methods, group sequential analysis (GSA), the sequential probability ratio test (SPRT) and the triangular test (TT) are well suited to randomized clinical trials with a censored response criterion, as they do not require matched pairs of patients. We undertook a simulation study to investigate their statistical properties and to compare these three methods with the fixed-sample design. Our results suggest that the three methods have the expected statistical properties for size and power; they allow an important reduction of the average number of events before stopping, except with GSA when there is no treatment difference; the triangular test (closed design) appears the optimal design, as the variance of the number of events is smaller than with the sequential probability ratio test (open design) and analysis after every twenty new events does not alter the statistical properties of these sequential methods and enhances their usefulness.  相似文献   
35.
伴ADHD的对立违抗性障碍儿童行为特征分析   总被引:6,自引:0,他引:6  
目的:了解伴注意缺陷/多动障碍(ADHD)的对立违抗性障碍(0DD)患儿的行为特征。方法:以ICD-10作为诊断标准对门诊就诊儿童进行诊断,得到ODD伴ADHD者40例(64.52%).ODD不伴ADHD者22例(35.48%)。自编家庭情况调查表调查患儿的基本情况。用家长填Achenbach儿章行为量表评定儿童行为。结果:与ODD组相比。合并ADHD组的家长更多对患儿经常打骂和严厉管教:对儿童的不良行为更多地采取打骂的方式。合并组父亲急燥易怒者比ODD组多;合并组起病年龄及就诊年龄比ODD组早:合并组在CBCI。思维、注意问题,违纪、攻击行为,外化性问题,行为总分均高于ODD组。结论:ODD合并ADHD的患儿在思维、注意问题,违纪、攻击行为,外化性问题方面表现更突出,家长对儿童管教方式及不良行为处理方式影响ODD的发生。提示要注重ODD、ADHD的早期干预。  相似文献   
36.
本研究建立了大鼠气管上皮细胞体内-体外转化模型,大鼠气管内滴注苯并芘,三天后处死大鼠,消化气管上皮细胞,接种于无血清完全培养基。细胞形成集落后,换为选择培养基继续培养五周,统计转化率。结果显示,25mg/kg和50mg/kg的苯并芘可诱导大鼠气管上皮细胞转化及微核增加,用同样方法研究了煤焦沥青提取物,结果表明,剂量为8mg/kg和25mg/kg的煤焦沥青提取物能明显诱导大鼠气管上皮细胞转化。  相似文献   
37.
Abstract Several previous studies have evaluated the effects of 0.12% chlorhexidine digluconate (ChD) mouthrinses on plaque and gingival inflammation. However, previously, none have been based in general dental practices. The aim of this study was to evaluate the potential to conduct controlled periodontal clinical trials in co-operation with general dental practitioners (gdps). The project took place in 5 general dental practices in the South of England. 121 healthy subjects (24 at 4 sites and 25 at the 5th). aged 18-65 years, mean 35 ± 12) years participated in a double-blind, randomised study during which they received full mouth assessments for plaque and gingival bleeding at baseline, 6 and 12 weeks. 60 subjects were randomly asigned to use the 0.12% ChD mouth wash and 6i the placebo. The assessments were carried out by 5 gpds, who had previously achieved inter-examiner κ scores of 0.78–0.85 (mean 0.81) for the plaque index (PlI), and of 0.73–0.94 (mean 0.87) for a modified gingival index (mGI), and who maintained κ scores of 0.51–0.90 for PII and of 0.73–1.00 for mGI during the 12 months required to complete the study. 98 subjects (48 ChD and 50 placebo) completed the study. Even though the baseline levels of plaque and gingivitis were low, by week 12, mean whole mouth piaque score of the ChD mouthwash users had fallen from 1.33 at baseline to 0.96 and was significantly lower (p < 0.001) than for the placebo users, 1.31 at baseline to 1.13. Whole-mouth gingival bleeding score fell from 0.56 to 0.42 in the ChD mouthwash group but was unchanged (0.54–0.55) in the placebo group. A subsidiary data analysis which considered the effects at sites indicated that within these overall differences, the ChD users experienced almost 2× the reduction from plaque score 2 at baseline at proximal molar sites over a 12-week period (50.6% ChD versus 27.6% placebo). It was concluded that 0.12% ChD mouthwash reduced plaque accumulation fay 28% and gingival inflammation by 25% over a 12–week period, that it is feasible for a group of gdps to maintain high levels of inter–examiner consistency in the use of PlI and mGI, that it is also feasible to carry out such a multicentre study in general dental practice, and that the use of mean mouth scores per subject to analyse the effects of mouthrinses may well mask variations in response throughout the mouth.  相似文献   
38.
In an open, randomized cross-over study in 124 patients, we compared the efficacy, safety and patient preference of oral and subcutaneous sum triptan in the acute treatment of migraine. Patients were treated for 3 attacks or 3 months and then crossed over. Primary clinical efficacy was defined as a reduction in headache severity on a four-point self-rating scale from severe (3) or moderate (2) to mild (1) or none (0), or mild (1) to none (0). Efficacy was evaluated 2 h after the administration of subcutaneous and 4h after the administration of oral sumatriptan. Subcutaneous sumatriptan was significantly more effective than oral sumatriptan in relieving headache (over all three attacks 78% vs 61% improvement), improving clinical disability (55% vs 41 % improvement) and relieving nausea (69% vs 53%), vomiting (72% vs 32%) and phono- or photophobia (67% vs 49%). Median time to recurrence was shorter after subcutaneous (12.5 h) than after oral sumatriptan (18 h); the number of patients experiencing a recurrence was similar Patients reported more adverse events after subcutaneous sumatriptan (1.32 per attack) than after the oral form (0.85 per attack), but all adverse events were mild to moderate in intensity and of short duration. Patient opinion was more often positive after subcutaneous sumatriptan. These results may be useful in counselling patients to choose between the available marketed formulations of sumatriptan.  相似文献   
39.
Osseointegrated dental implants have now become an accepted form of treatment for patients with a fully or partially missing dentition. The purpose of this study was to evaluate the performance of 3i threaded and cylindrical implants. During a 5-year period, a total of 1969 3i endosseous implants were placed at 6 centers in the United States and 2 elsewhere in the edentulous and partially edentulous jaws of 653 consecutive patients ranging in age from 18 to 82 years. Of the total number of implants placed, 1341 were commercially pure titanium threaded implants and 628 were titanium plasma-sprayed implants with a cylindrical configuration. A total of 28 patients with 110 implants were lost to follow-up. Implants in these patients were considered neither a success nor a failure. Success was predicated on the osseointegration of each and every implant followed in this analysis rather than the persistence of prosthetic function. Confirmed bone anchorage was considered essential for success. A total of 625 patients with 1871 implants remain in the study with a follow-up period ranging from 6 to 60 months. A total of 93 implants (5.0% of the total implants followed) were considered as failures. A mean implant survival rate was 95.0% for both the threaded and the cylindrical implant was calculated. The success rate of threaded implants was 97.0% in the mandible and 93.8% in the maxilla. The success rate for the 3.3mm cylindrical implants was 96.0% in the mandible and 95.5% in the maxilla, and the success rate of 4.0mm diameter cylindrical implants was 95% in the mandible and 92.0% in the maxilla. Causes of failure consisted of loss of osseointegration 2.3%crestal bone loss requiring periodontal therapy after the first year of function 1.7% and mechanical problems associated with the prosthesis 0.9%. This retrospective analysis of the 3i endosseous implant system is comparable to previous reports on other implant systems in terms of implant survival and prosthesis stability. It is demonstrated that 3i implants are predictable and can provide lasting osseointegration leading to improvement of oral function if the recommended surgical and restorative protocol is followed.  相似文献   
40.
房间隔入路的解剖学研究及临床应用   总被引:3,自引:0,他引:3  
对33具尸体的房间隔的大小、构成及周围重要组织结构进行观察和测量。提出房间隔切开时的正确方向、安全长度及可能发生的危险。结合466例临床应用,讨论了避免切口合并症发生及发生后的正确处理方法。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号